The Boulder Valley School Board wisely rejected a proposal on Tuesday night that would have delayed school starting by only four days next fall. Parental concerns about unbearable classroom heat in August were valid. Teachers unwilling to move their professional days to before school starts may be less so. However, four days simply is not enough of a change.

In the 1980s and 1990s, school started after Labor Day most of the time. September’s first days were often warm for fall clothes, so students dressed accordingly. To think students did any differently this year is ridiculous when school began Aug. 15 and temperatures outside reached 98 degrees.

The purported reason for increasingly early starts and their intrusion into time with family is to allow students to take semester finals before Christmas break. Thus, students wouldn’t have tests hanging over their heads during the break. However, when school started after Labor Day, students had plenty of time to get back into their studies before finals. A big plus, too, was schools weren’t too hot.

Instead of adjusting the calendar only four days, the school board should do the smart thing for learning and for the health of children. It should direct future calendar committees to have school start no earlier than the last Monday in August. The preference would be after Labor Day.

If the board is unwilling to do that, it should call “snow days” or “inclement weather days” when temperatures outside climb to make classrooms stifling without air-conditioning. Heat stressed children don’t learn well, and they risk heat exhaustion and heat stroke as well.

The school board protects students against freezing temperatures, snow and ice. It must do the same for students against excessive heat.